Web site SharedCopy lets you share and mark up full web pages with a simple bookmarklet.

After you add the SharedCopy bookmarklet to your toolbar, just click it when you find a page you want to mark up and share. You can then add text notes, simple lines and shapes, and highlights to the page. When you're done, click save and grab the URL for your SharedCopy page and share it with anyone for a simple way to collaborate. To get an idea of how it works, check out this page on Lifehacker that I marked up for sharing earlier today. For an alternate take on web page sharing and annotation, check out previously mentioned Jump Knowledge. — Adam Pash